JP2008049230A - Atomizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an atomizer which prevents a reduction in atomizing capacity and/or keeps a stability in atomization. <P>SOLUTION: A vibration part 12 is intermittently vibrated by applying a signal exciting a piezoelectric element 11 constituting a vibrator 10 to the piezoelectric element 11 intermittently at a predetermined cycle through cooperating the burst circuit 21 of an exciting circuit 20 and a switch circuit 22. Stopping due to intermittent operation of the vibration part 12 avoids a deposit of excess water W on a top end 12F to prevent excessive loads to the vibration part 12, not to reduce the atomizing capacity and to stably continue atomization. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an atomization apparatus that atomizes a liquid by vibrating a vibrator using a piezoelectric element.
In particular, the present invention relates to a technique for improving a decrease in atomization performance and / or instability of atomization.

  Patent Document 1 discloses an ultrasonic humidifier vibrator used in an ultrasonic humidifier or the like.

FIG. 1 is a diagram illustrating a method of generating mist (atomization) with ultrasonic waves using a vibrator.
The vibrator 10 includes a piezoelectric element 11, a vibrating part 12, and a fixed part (or base part) 13. The piezoelectric element 11 and the vibration part 12 are connected via a fixed part (or base part) 13.
The piezoelectric element 11 is, for example, PZT, and vibrates at a natural frequency of PZT in a direction indicated by an arrow A1 when a voltage is applied.
The vibration part 12 has, for example, a curved part 12A having a curved cross section and a cylindrical part 12B having a flat cross section, vibrates according to the vibration of the piezoelectric element 11, and is shown in the direction of the arrow A2. It vibrates in the longitudinal direction.
The water supply cotton 50 is in contact with the lower portion of the tip 12F of the cylindrical portion 12B of the vibrating portion 12. The water W from the water supply cotton 50 rises on the surface of the tip 12F of the cylindrical portion 12B by the vibration of the vibrating portion 12.
The water W adhering to the surface of the tip 12F of the cylindrical part 12B is atomized by the high-speed vibration of the vibration part 12.

Devices such as an ultrasonic atomizer, an ultrasonic agitator, and an ultrasonic cleaner manufactured according to the atomization principle described above are in practical use.
Patent No. 2,652,440

In the atomization method described with reference to FIG. 1, it has been found that when atomization is continuously performed, the atomization performance is deteriorated and / or the atomization becomes unstable.
For example, if the atomization is continuously performed, the fog generated by the atomization decreases, and eventually, there is a possibility that the atomization cannot be continued stably.

  An object of the present invention is to provide an atomizing device in which the atomization performance does not deteriorate even when operated for a long time and / or the atomization can be stably continued.

According to the inventor's consideration and experiment, the above-described degradation of the atomization performance and / or instability of the atomization is due to the continuous operation of the atomization, as illustrated in FIG. It has been found that the amount of water W adhering from the cotton 50 to the surface of the tip 12F of the cylindrical portion 12B may increase. That is, the water supplied from the water supply cotton 50 excessively moves up the surface of the tip 12F due to the vibration of the vibration unit 12.
When the amount of water adhering to the surface of the tip 12F increases, an excessive load is applied to the vibration unit 12. That is, when the amount of water adhering to the surface of the tip 12F increases, the increased water cannot be atomized by the vibration force of the vibration part 12, and the vibration force of the vibration part 12 is insufficient, and the atomization ability is reduced. The present inventors have found that the atomization is reduced and / or the atomization becomes unstable.

  Although the above-mentioned problem can be overcome by making the vibration part 12 large, naturally the piezoelectric element 11 needs to be large. Increasing the size of the piezoelectric element 11 causes an increase in the excitation power of the piezoelectric element 11, resulting in a problem that the excitation circuit becomes larger. Alternatively, the drive frequency is limited.

In order to avoid the occurrence of the above-described new problem and overcome the above-described problem, the amount of water W adhering to the surface of the tip 12F of the cylindrical portion 12B from the water supply cotton 50 is more than the amount to be atomized. It is desirable not to increase it.
For that purpose, it is desirable that the vibration of the vibrating part 12 is intermittently stopped while the atomized state is substantially continued, so that excessive water W does not adhere to the tip 12F of the cylindrical part 12B. I understood.

  According to the inventor's experiment, when the vibration of the vibration part 12 is stopped instantaneously, excessive water does not adhere to the surface of the tip 12F of the vibration part 12 while the atomization is substantially performed. It has been found that the atomization performance does not deteriorate and / or the atomization is stable.

  According to the present invention, the atomization includes a vibrator having a piezoelectric element, a vibration part connected to the piezoelectric element, and an excitation circuit for exciting the piezoelectric element, and atomizes the liquid in the vibration part. An atomization apparatus is provided, wherein the excitation circuit includes an intermittent excitation circuit that excites the piezoelectric element intermittently at a predetermined period.

  Preferably, the intermittent excitation circuit is configured to apply a burst pulse signal to the piezoelectric element when the excitation of the piezoelectric element is started.

According to the present invention, the atomization performance does not decrease and / or the atomization can be stably continued while the atomization is substantially continued.
The meaning that the atomization performance does not decrease and / or the atomization can be stably continued means that the atomization performance does not decrease, the atomization performance can be stably continued without deterioration, Or it means that atomization can be continued stably.

  The atomization apparatus according to the embodiment of the present invention includes the vibrator 10 illustrated in FIG. 1 or 2, the excitation circuit 20 illustrated in FIG. 3, and the water supply cotton 50.

  As illustrated in FIG. 1 or FIG. 2, the vibrator 10 includes a piezoelectric element 11, a vibrating part 12, and a fixed part (or base part) 13. The vibration part 12 has a curved part 12A and a cylindrical part 12B, and the water supply cotton 50 contacts the lower surface of the cylindrical part 12B so that water W can be supplied to the surface of the tip 12F.

FIG. 3 is a diagram showing a circuit of an embodiment of an excitation circuit applied to the atomization apparatus of the present invention.
The excitation circuit 20 that excites the piezoelectric element 11 of the vibrator 10 includes a burst circuit 21, a switch circuit 22, a step-up transformer 23, a drive current detector 24, a voltage divider 25, a comparator 26, and a reference voltage generator. And a voltage controlled oscillator (VCO) 28.
The excitation circuit 20 is an excitation circuit capable of frequency control according to the load illustrated in FIG. Therefore, a negative feedback circuit using the drive current detector 24, the voltage divider 25, the comparator 26, the reference voltage generator 27, and the VCO 28 is configured.

The operation of the excitation circuit 20 will be described.
An AC power supply (not shown) is applied to the burst circuit 21.
As illustrated in FIG. 5, the burst circuit 21 intermittently operates at a predetermined cycle τ and outputs a burst-like pulse signal.
In response to the output signal of the burst circuit 21, the switch circuit 22 outputs the output signal from the VCO 28 to the step-up transformer 23.
When a signal from the VCO 28 is applied to the step-up transformer 23, the step-up transformer 23 boosts the signal to a voltage level at which the piezoelectric element 11 can be driven and applies it to the piezoelectric element 11.
Thereby, the piezoelectric element 11 is excited and vibrates, and the vibration unit 12 vibrates as described with reference to FIG. 1 according to the driving of the piezoelectric element 11. Thereby, the water W supplied from the water supply cotton 50 to the surface of the tip 12F of the vibrating portion 12 is atomized.

  The drive current detector 24 detects a drive current corresponding to the load of the piezoelectric element 11 and outputs it to the voltage divider 25. The load of the piezoelectric element 11 means the amount of water W adhering to the tip 12F of the vibration unit 12 connected to the piezoelectric element 11. If the amount of water W adhering to the tip 12F is large, it means that the load on the vibrating part 12, that is, the piezoelectric element 11 is heavy. On the other hand, if the amount of water W adhering to the tip 12F is small, it means that the load on the vibrating part 12, that is, the piezoelectric element 11 is light. In this way, the excitation circuit 20 controls the frequency applied to the piezoelectric element 11 according to the load of the piezoelectric element 11, in other words, the vibration unit 12, in other words, the oscillation frequency of the VCO 28.

The relationship between the voltage obtained by rectifying the current detected by the drive current detector 24 and the oscillation frequency generated by the VCO 28 is as illustrated in FIG.
fr is the resonance frequency. The reference voltage generator 27 outputs a reference voltage Vr corresponding to the resonance frequency fr to the VCO 28.
In FIG. 4, a curve CV1 indicates the frequency characteristic when the load is in the reference state, a curve CV2 indicates the frequency characteristic when the load is heavy, and a curve CV3 indicates the frequency characteristic when the load is light.

Although the voltage divider 25 is not an essential circuit in the excitation circuit 20, a voltage corresponding to the detection current of the drive current detector 24 is divided and output to the comparator 26.
The comparator 26 outputs to the VCO 28 the difference voltage between the reference voltage Vr corresponding to the resonance frequency fr from the reference voltage generator 27 and the output signal from the voltage divider 25.
The VCO 28 generates an oscillation signal having a frequency corresponding to the input voltage and outputs the oscillation signal to the switch circuit 22.
From the above, the piezoelectric element 11 is excited at the oscillation frequency generated by the VCO 28 according to the load of the vibration unit 12.

As illustrated in FIG. 5, the oscillation frequency signal of the VCO 28 is intermittently (periodically) with a period τ by the cooperation of the burst circuit 21 and the switch circuit 22 constituting the intermittent excitation circuit of the present invention. By outputting to the step-up transformer 23, the water adhering to the surface of the tip 12F is properly maintained by stopping the excitation of the piezoelectric element 11 and stopping the vibration of the vibration part 12, and thus the atomization performance is improved. It does not decrease and / or atomization is performed stably and continuously.
The reason is that when the vibration part 12 continuously vibrates, the water W from the water supply cotton 50 rises up the surface of the tip 12F due to the vibration, but when the vibration of the vibration part 12 stops, the water supply cotton 50 This is because the amount of water W rising from the surface of the tip 12F to the surface of the tip 12F is reduced, and the amount of water W adhering to the surface of the tip 12F is appropriately maintained. In other words, excessive water W is not supplied to the surface of the tip 12F. Therefore, it is possible to avoid the performance degradation of the vibration unit 12 and / or the instability of atomization due to excessive water.

In particular, as illustrated in FIG. 5, by using a burst-like signal with a period τ, the voltage applied to the piezoelectric element 11 using the transient response at the time of rising of the piezoelectric element 11 is increased, and stable atomization is achieved. Can be made. That is, the heat generation of the vibrator 10 can be suppressed and the vibrator 10 can be operated stably.
The period τ is, for example, several tens Hz to 100 Hz.

Needless to say, the vibrator 10 is not limited to the vibrator 10 having the structure illustrated with reference to FIGS. 1 and 2.
Similarly, since water should just be supplied to the part of the surface of the front-end | tip 12F, when using the cotton-like water supply cotton 50, it is not limited. For example, water may be supplied to the surface of the tip 12F by capillary action.

  In the excitation circuit 20 illustrated in FIG. 3, the burst-like pulse signal only needs to be applied to the piezoelectric element 11, so that the burst-like pulse signal is not provided in the portion illustrated in FIG. A circuit for applying a voltage to the piezoelectric element 11 may be provided.

  FIG. 5 shows a case where a burst signal is intermittently applied to the piezoelectric element 11 as a preferred example. However, since it is sufficient that the piezoelectric element 11 is stopped periodically, Alternatively, it may be a rectangular pulse signal that is turned on / off at a predetermined cycle.

FIG. 1 is a diagram showing the principle of atomization using a vibrator having a piezoelectric element and a vibrating part. FIG. 2 is a diagram illustrating a decrease in atomization performance using a vibrator having a piezoelectric element and a vibrating portion. FIG. 3 is a circuit diagram of an excitation circuit for exciting the piezoelectric element of the vibrator. FIG. 4 is a diagram showing the frequency characteristics of the vibrator. FIG. 5 is a waveform diagram of a burst signal by the burst circuit in the excitation circuit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Vibrator, 11 ... Piezoelectric element, 12 ... Vibrating part, 12A ... Curve part, 12B ... Cylindrical part, 12F ... Tip, 20 ... Excitation circuit, 21 ... Burst circuit, 22 ... Switch circuit, 23 ... Step-up transformer, 24 ... Drive current detector, 25 ... Voltage divider, 26 ... Comparator, 27 ... Reference voltage generator, 28 ... Voltage controlled oscillator (VCO)

Claims (2)

A vibrator having a piezoelectric element and a vibrating portion connected to the piezoelectric element;
An excitation circuit for exciting the piezoelectric element,
An atomizing device for atomizing a liquid in the vibration unit,
The excitation circuit includes an intermittent excitation circuit that excites the piezoelectric element intermittently at a predetermined period.
Atomization device. The intermittent excitation circuit is configured to apply a burst-like pulse signal to the piezoelectric element when excitation of the piezoelectric element is started.
The atomization apparatus of Claim 1.

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